Detailed Description
The technical solutions of the present invention will be described in detail and fully with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The transparent conductive film comprises a transparent carrier, a conductive layer and a protective layer, wherein the conductive layer and the protective layer are sequentially coated on the transparent carrier; the protective layer comprises acrylic resin, mixed solvent and coloring agent.
Aiming at the problem that the color of the existing transparent conductive film is easy to change due to the fact that the conductive layer is coated with more conductive materials, the color changing effect of the conductive layer is compensated by adding a coloring agent into the protective layer based on the color feeling of a human body according to a CIE Lab color model; the colorless and transparent visual effect of the conductive film is realized by utilizing the superposition of the color of the coloring agent in the protective layer and the color of the discolored conductive layer, and the visibility and the transmittance of the conductive film are improved.
The CIE Lab color model is a physiological feature based color system. Lab color model consists of three elements, brightness L and two color channels a, b; a comprises colors from dark green (low brightness value) to gray (medium brightness value) to bright pink (high brightness value); b includes colors ranging from bright blue (low luminance value) to gray (medium luminance value) to yellow (high luminance value). All colors can be measured perceptually by Lab x-bars, which can be used to represent the color difference of the same sample as the standard, and are usually identified by Δ. If the delta L is positive, the sample is lighter than the standard sample, and if the delta L is negative, the sample is darker than the standard sample; if Δ a is positive, the sample is red (or less green) than the standard, and if Δ a is negative, the sample is green (or less red) than the standard; if Δ b is positive, the sample is yellow (or less blue) than the standard, and if Δ b is negative, the sample is blue (or less yellow) than the standard.
Therefore, by using the CIE Lab color model, the protective layer coloring agent with different compensation colors is correspondingly selected according to the colors displayed by different conductive layers, so that the effects of improving the visibility and the transmittance of the conductive film from the visual angle are realized.
Specifically, the components of the protective layer also comprise an initiator and a leveling agent, and the initiator and the leveling agent are mixed according to the following parts by weight: 5-10 parts of acrylic resin, 80-90 parts of mixed solvent, 2-5 parts of initiator, 1-3 parts of flatting agent and coloring agent accounting for 0.01-0.05 wt% of the total amount of the components.
Specifically, the acrylic resin is one or more of epoxy acrylic resin, polyurethane acrylic resin and polyester acrylic resin; the initiator is one or more of 2,4,6 (trimethylbenzoyl) diphenylphosphine oxide, 1-hydroxy-cyclohexyl-monophenyl ketone and 2-hydroxy-2-methyl-1-phenyl-1-acetone; the leveling agent is polyether modified siloxane, such as BYK333, BYK306/307, Digao 450, and the like.
Specifically, the preparation method of the protective layer comprises the following steps: adding acrylic resin, the mixed solution, an initiator and a flatting agent into a container according to the proportion, stirring and mixing uniformly to obtain a mixed solution, adding a coloring agent accounting for 0.01-0.05 wt% of the total amount of the mixed solution, stirring for 30-40min, fully mixing uniformly to obtain a protective layer coating liquid, and coating and curing the protective layer coating liquid on the surface of the conductive layer to obtain the conductive coating.
Preferably, the protective layer coating liquid is coated on the conductive layer in a slit coating mode, the coating speed is 180-220cm/min, and the curing temperature is 60-130 ℃.
Specifically, the conductive layer is conductive paste coated and cured on the surface layer of the transparent carrier, and the conductive paste is one or a mixture of silver nanowires, gold nanowires, copper nanowires, nickel nanowires, silver nanoparticles, gold nanoparticles, copper nanoparticles and nickel nanoparticles. When the raw materials in the conductive paste are different, the colors and the brightness displayed by the conductive film are different, and the coloring agents with different amounts and colors are correspondingly selected as the components of the protective layer according to the CIE Lab color model to be coated, so that the effect of improving the transmittance of the conductive film is achieved through the compensation between the two colors.
Preferably, the conductive layer is silver nanowire conductive paste. More specifically, the silver nanowire conductive paste is uniformly coated on the surface of the transparent carrier in a slit coating mode, the coating speed is 80-120cm/min, the curing temperature is 70-130 ℃, the pump speed is 20-80ml/min, and the wet film thickness is 10-80 μm.
Specifically, the silver nanowire conductive paste comprises 0.1-0.5 wt% of silver nanowires, the diameter of each silver nanowire is 10-100nm, and the length-diameter ratio is more than or equal to 1000.
Specifically, the transparent carrier is any one of PET, COP, TAC, PVC, PI and PE.
Specifically, the mixed solution is formed by mixing an alcohol solvent, a ketone solvent, an ester solvent and an ether solvent according to the mass ratio of 1:1:1: 1. Preferably, the alcohol solvent may be methanol, ethanol, propanol, butanol, etc.; the ketone solvent can be acetone, butanone, methyl pentanone, methyl isobutyl ketone, cyclohexanone, etc.; the ester solvent can be ethyl acetate, butyl acetate, isopropyl acetate, etc.; the ether solvent can be diethylene glycol monomethyl ether, propylene glycol methyl ether, dipropylene glycol dimethyl ether, diethylene glycol butyl ether, propylene glycol butyl ether, etc.
Specifically, the coloring agent is a blue coloring agent. As too much silver nanowires resulted in yellowing of the conductive film, the sample was more yellow (or less blue) than the standard according to CIE Lab color model, i.e. Δ b is positive. Therefore, in order to compensate and neutralize the color of the conductive film, the conductive film is realized by adding a blue coloring agent, further the yellowing effect is reduced or eliminated, the b value is reduced, and the Delta b tends to zero, so that the visual effect of the conductive film is improved.
More specifically, the blue coloring agent is one or more of alizarin blue, basic blue 6B, alcohol blue, water-soluble aniline blue, azo blue, brilliant cresol blue, bromophenol blue, carbazole blue, quinoline blue, indigo blue, resin phenol blue, methyl blue, methine blue, patent blue A, patent blue V, phthalocyanine, resazurin, benzylazurin, prussian blue, methylene benzene blue, thymol blue and tricresyl blue.
Experimental studies have shown that at low b*In the preparation process of the silver nanowire conductive film, not all blue coloring agents can play a good role in reducing the yellowing of the silver nanowires, and particularly, the blue coloring agents need to meet the following conditions:
(1) the blue coloring agent has certain solubility in mixed solvent of alcohol, ketone, ester and ether; the blue coloring agent can be uniformly dissolved in the coating liquid of the protective layer, so that the conductive layer can be uniformly coated conveniently, the yellow compensation effect of the conductive layer is uniform, and the yellowing effect of the conductive film is well reduced.
(2) The blue dye has strong absorption band in visible light region, and molar absorptivity (epsilon) greater than 104(ii) a The blue coloring agent meeting the condition has better color development capability, and can achieve the effects of reducing b value and preventing the silver nanowire conductive film from yellowing under the application condition of less blue coloring agent.
(3) The blue coloring agent has higher melting point or decomposition temperature; because the silver nanowire conducting film needs to be subjected to gradient heating and cooling heat treatment in the preparation process, the blue coloring agent needs to be kept in the temperature range and has stable performance.
Specifically, the thickness of the transparent carrier is 0.01-0.3 mm; the thickness of the conductive layer is 100-300 nm; the thickness of the protective layer is 80-300 nm. More specifically, the transmittance of the transparent carrier is more than 95%, the surface resistance of the conductive layer is 5-100 omega, and the transmittance is more than 90%
The silver nanowire conducting layer is coated with the protective layer with the blue coloring agent, so that the b value can be effectively reduced, and the yellowing problem of the silver nanowire conducting film is solved. The resistance of the conductive film with the blue colorant added was measured as a function of b, and the results are shown in table 2.
TABLE 2 resistance of silver nanowire conductive film and b*Value relationship (adding coloring agent)
R (omega/mouth)
|
30
|
20
|
10
|
5
|
b*Value (%)
|
3.5
|
4.0
|
5.5
|
6.0 |
Comparing table 2 with table 1, it can be seen that b of the silver nanowire conductive film added with the blue coloring agent is obviously reduced under the same resistance condition, so that the yellowing effect of the conductive film is effectively relieved, and the visibility of the conductive film is improved.
To more specifically illustrate the effect of the transparent conductive film of the present invention in improving the transmittance of the conductive film, the silver nanowire conductive paste is taken as an example to illustrate the difference between the silver nanowire conductive film and the existing silver nanowire conductive film without adding a coloring agent or a protective layer, and the following description will be further made with reference to specific examples and comparative examples.
Example 1
Uniformly coating silver nanowire slurry on the surface of PET (polyethylene terephthalate) by using PET as a transparent carrier in a slit coating mode, wherein the pumping speed is 30ml/min, the wet film thickness is 30 mu m, the coating speed is 100cm/min, and the curing temperature is 70 ℃ to form a uniform conductive layer;
adding 6 parts of acrylate resin, 90 parts of (ethanol: butanone: ethyl acetate: diethylene glycol monomethyl ether) mixed solvent with the mass ratio of 1:1:1:1, 2 parts of initiator 2,4,6 (trimethylbenzoyl) diphenyl phosphine oxide and 2 parts of flatting agent BYK 3332 into a glass container, stirring and mixing uniformly to obtain a mixed solution, adding an alkaline blue 6B blue coloring agent accounting for 0.02 wt% of the total amount of the mixed solution into the mixed solution, stirring for 30min, and mixing uniformly to obtain a protective layer coating liquid;
and coating the protective layer coating liquid on the conductive layer in a slit coating mode at the coating speed of 200cm/min and the curing temperature of 60 ℃ to form a compact protective layer, thus obtaining the silver nanowire conductive film.
Comparative example 1.1
Uniformly coating silver nanowire slurry on the surface of PET (polyethylene terephthalate) by using PET as a transparent carrier in a slit coating mode, wherein the pumping speed is 30ml/min, the wet film thickness is 30 mu m, the coating speed is 100cm/min, and the curing temperature is 70 ℃ to form a uniform conductive layer;
adding 6 parts of acrylate resin, 90 parts of (ethanol: butanone: ethyl acetate: diethylene glycol monomethyl ether) mixed solvent with the mass ratio of 1:1:1:1, 2 parts of initiator 2,4,6 (trimethylbenzoyl) diphenyl phosphine oxide and 2 parts of flatting agent BYK 3332 into a glass container, and uniformly stirring and mixing to obtain a protective layer coating liquid;
and coating the protective layer coating liquid on the conductive layer in a slit coating mode at the coating speed of 200cm/min and the curing temperature of 60 ℃ to form a compact protective layer, thus obtaining the silver nanowire conductive film.
Comparative example 1.2
And (2) uniformly coating the silver nanowire slurry on the surface of the PET by using the PET as a transparent carrier in a slit coating mode, wherein the pumping speed is 30ml/min, the wet film thickness is 30 mu m, the coating speed is 100cm/min, and the curing temperature is 70 ℃ to form a uniform conductive layer, so that the silver nanowire conductive film is prepared.
The silver nanowire conductive films obtained in example 1 and comparative examples 1.1 and 1.2 were subjected to resistance, transmittance, haze, b-value tests, and the test results are shown in table 3.
Table 3 silver nanowire conductive film test results
Group of
|
Resistance (omega/port)
|
Transmittance (%)
|
Haze (%)
|
b*(%)
|
Example 1
|
30
|
91.5
|
1.2
|
3.5
|
Comparative example 1.1
|
30
|
91.5
|
1.4
|
5.5
|
Comparative example 1.2
|
30
|
91.2
|
1.5
|
5.5 |
More specifically, the silver nanowire conductive film prepared in example 1 was subjected to a weather resistance test in the following manner:
UV resistance test: irradiation intensity of 0.35W/M2At the temperature of 60 ℃ for 240 h;
xenon weather resistance test: radiation intensity 0.8W/M2The temperature is 40 ℃, the humidity is 55 percent, and the time is 240 h;
high temperature and high humidity test: the temperature is 85 ℃, the humidity is 85 percent, and the time is 240 h;
and (3) testing cold and hot impact: the temperature is low at-30 ℃ and high at 90 ℃ for 240 hours.
The results of the weather resistance test of the silver nanowire conductive film prepared in example 1 are shown in table 4.
Table 4 weather resistance test results of silver nanowire conductive film
Wherein: and (3) testing the adhesive force: BYK hundred grid knife &3M610 tape; chemical resistance: MEK 5 wipes to test resistance change
Example 2
Uniformly coating silver nanowire slurry on the surface of PET (polyethylene terephthalate) by taking PET as a transparent carrier in a slit coating mode, wherein the pumping speed is 50ml/min, the wet film thickness is 40 mu m, the coating speed is 80cm/min, and the curing temperature is 100 ℃ to form a uniform conductive layer;
adding 7 parts of acrylate resin, 88 parts of mixed solvent (ethanol: butanone: ethyl acetate: diethylene glycol monomethyl ether) with the mass ratio of 1:1:1:1, 3 parts of initiator 2-hydroxy-2-methyl-1-phenyl-1-acetone and 3 parts of flatting agent BYK 3062 into a glass container, stirring and mixing uniformly to obtain a mixed solution, adding a bromophenol blue coloring agent accounting for 0.03 wt% of the total amount of the mixed solution into the mixed solution, stirring for 40min, and mixing uniformly to obtain a protective layer coating liquid;
and coating the protective layer coating liquid on the conductive layer in a slit coating mode, wherein the coating speed is 180cm/min, the curing temperature is 100 ℃, and a compact protective layer is formed to obtain the silver nanowire conductive film.
Comparative example 2.1
Uniformly coating silver nanowire slurry on the surface of PET (polyethylene terephthalate) by taking PET as a transparent carrier in a slit coating mode, wherein the pumping speed is 50ml/min, the wet film thickness is 40 mu m, the coating speed is 80cm/min, and the curing temperature is 100 ℃ to form a uniform conductive layer;
adding 7 parts of acrylate resin, 88 parts of (ethanol: butanone: ethyl acetate: diethylene glycol monomethyl ether) mixed solvent with the mass ratio of 1:1:1:1, 3 parts of initiator 2-hydroxy-2-methyl-1-phenyl-1-acetone and 3062 parts of flatting agent BYK 3062 into a glass container, and uniformly stirring and mixing to obtain a protective layer coating liquid;
and coating the protective layer coating liquid on the conductive layer in a slit coating mode, wherein the coating speed is 180cm/min, the curing temperature is 100 ℃, and a compact protective layer is formed to obtain the silver nanowire conductive film.
Comparative example 2.2
And (2) uniformly coating the silver nanowire slurry on the surface of the PET by using the PET as a transparent carrier in a slit coating mode, wherein the pumping speed is 50ml/min, the wet film thickness is 40 mu m, the coating speed is 80cm/min, and the curing temperature is 100 ℃ to form a uniform conductive layer, so that the silver nanowire conductive film is prepared.
The silver nanowire conductive films obtained in example 2 and comparative examples 2.1 and 2.2 were subjected to resistance, transmittance, haze, b-value tests, and the test results are shown in table 5.
Table 5 silver nanowire conductive film test results
Group of
|
Resistance (omega/port)
|
Transmittance (%)
|
Haze (%)
|
b*(%)
|
Example 1
|
10
|
90.8
|
1.6
|
5.5
|
Comparative example 2.1
|
10
|
90.5
|
1.8
|
8.0
|
Comparative example 2.2
|
10
|
90.0
|
1.8
|
8.0 |
More specifically, the silver nanowire conductive film obtained in example 2 was subjected to a weather resistance test under the same conditions as in example 1, and the weather resistance test results are shown in table 6.
Table 6 weather resistance test results of silver nanowire conductive film
Example 3
Uniformly coating silver nanowire slurry on the surface of PET (polyethylene terephthalate) by taking PET as a transparent carrier in a slit coating mode, wherein the pumping speed is 55ml/min, the wet film thickness is 45 mu m, the coating speed is 120cm/min, and the curing temperature is 130 ℃ to form a uniform conductive layer;
adding 10 parts of acrylate resin, 82 parts of (ethanol: butanone: ethyl acetate: diethylene glycol monomethyl ether) mixed solvent with the mass ratio of 1:1:1:1, 5 parts of initiator 1-hydroxy-cyclohexyl-phenyl ketone and 4503 parts of flatting agent into a glass container, stirring and mixing uniformly to obtain a mixed solution, adding a bromophenol blue coloring agent accounting for 0.05 wt% of the total amount of the mixed solution into the mixed solution, stirring for 35min, and mixing uniformly to obtain a protective layer coating liquid;
and coating the protective layer coating liquid on the conductive layer in a slit coating mode, wherein the coating speed is 220cm/min, the curing temperature is 130 ℃, a compact protective layer is formed, and the silver nanowire conductive film is prepared.
Comparative example 3.1
Uniformly coating silver nanowire slurry on the surface of PET (polyethylene terephthalate) by taking PET as a transparent carrier in a slit coating mode, wherein the pumping speed is 55ml/min, the wet film thickness is 45 mu m, the coating speed is 120cm/min, and the curing temperature is 130 ℃ to form a uniform conductive layer;
adding 10 parts of acrylate resin, 82 parts of (ethanol: butanone: ethyl acetate: diethylene glycol monomethyl ether) mixed solvent with the mass ratio of 1:1:1:1, 5 parts of initiator 1-hydroxy-cyclohexyl-phenyl ketone and 4503 parts of flatting agent into a glass container, and uniformly stirring and mixing to obtain a protective layer coating liquid;
and coating the protective layer coating liquid on the conductive layer in a slit coating mode, wherein the coating speed is 220cm/min, the curing temperature is 130 ℃, a compact protective layer is formed, and the silver nanowire conductive film is prepared.
Comparative example 3.2
And (2) uniformly coating the silver nanowire slurry on the surface of the PET by using the PET as a transparent carrier in a slit coating mode, wherein the pumping speed is 55ml/min, the wet film thickness is 45 mu m, the coating speed is 120cm/min, and the curing temperature is 130 ℃, so that a uniform conductive layer is formed, and the silver nanowire conductive film is prepared.
The silver nanowire conductive films obtained in example 3 and comparative examples 3.1 and 3.2 were subjected to resistance, transmittance, haze, b-value tests, and the test results are shown in table 7.
Table 7 silver nanowire conductive film test results
Group of
|
Resistance (omega/port)
|
Transmittance (%)
|
Haze (%)
|
b*(%)
|
Example 3
|
5
|
90.0
|
1.9
|
6.0
|
Comparative example 3.1
|
5
|
90.0
|
2.0
|
10.0
|
Comparative example 3.2
|
5
|
89.5
|
2.0
|
10.0 |
More specifically, the silver nanowire conductive film obtained in example 3 was subjected to a weather resistance test under the same conditions as in example 1, and the weather resistance test results are shown in table 8.
Table 8 weather resistance test results of silver nanowire conductive film
Example 4
Uniformly coating silver nanowire slurry on the surface of PET (polyethylene terephthalate) by using TAC (sulfoviny acid) as a transparent carrier in a slit coating mode, wherein the pumping speed is 20ml/min, the wet film thickness is 15 mu m, the coating speed is 100cm/min, and the curing temperature is 70 ℃ to form a uniform conductive layer;
adding 5 parts of acrylate resin, 80 parts of (ethanol: butanone: ethyl acetate: diethylene glycol monomethyl ether) mixed solvent with the mass ratio of 1:1:1:1, 3 parts of initiator 2,4,6 (trimethylbenzoyl) diphenyl phosphine oxide and 3 parts of flatting agent BYK 3331 into a glass container, stirring and mixing uniformly to obtain a mixed solution, adding alizarin blue coloring agent accounting for 0.01 wt% of the total amount of the mixed solution into the mixed solution, stirring for 30min, and mixing uniformly to obtain a protective layer coating liquid;
and coating the protective layer coating liquid on the conductive layer in a slit coating mode at the coating speed of 200cm/min and the curing temperature of 60 ℃ to form a compact protective layer, thus obtaining the silver nanowire conductive film.
Comparative example 4.1
Uniformly coating silver nanowire slurry on the surface of PET (polyethylene terephthalate) by using TAC (sulfoviny acid) as a transparent carrier in a slit coating mode, wherein the pumping speed is 20ml/min, the wet film thickness is 15 mu m, the coating speed is 100cm/min, and the curing temperature is 70 ℃ to form a uniform conductive layer;
adding 5 parts of acrylate resin, 80 parts of (ethanol: butanone: ethyl acetate: diethylene glycol monomethyl ether) mixed solvent with the mass ratio of 1:1:1:1, 3 parts of initiator 2,4,6 (trimethylbenzoyl) diphenyl phosphine oxide and 3 parts of flatting agent BYK 3331 into a glass container, and uniformly stirring and mixing to obtain a protective layer coating liquid;
and coating the protective layer coating liquid on the conductive layer in a slit coating mode at the coating speed of 200cm/min and the curing temperature of 60 ℃ to form a compact protective layer, thus obtaining the silver nanowire conductive film.
Comparative example 4.2
And (3) taking TAC as a transparent carrier, uniformly coating the silver nanowire slurry on the surface of PET in a slit coating mode, wherein the pumping speed is 20ml/min, the wet film thickness is 15 mu m, the coating speed is 100cm/min, and the curing temperature is 70 ℃, so that a uniform conductive layer is formed, and the silver nanowire conductive film is prepared.
The silver nanowire conductive films obtained in example 4 and comparative examples 4.1 and 4.2 were subjected to resistance, transmittance, haze, b-value tests, and the test results are shown in table 9.
Table 9 silver nanowire conductive film test results
Group of
|
Resistance (omega/port)
|
Transmittance (%)
|
Haze (%)
|
b*(%)
|
Example 4
|
100
|
94.5
|
0.8
|
1.0
|
Comparative example 4.1
|
100
|
94.5
|
1.0
|
2.0
|
Comparative example 4.2
|
100
|
93.5
|
1.0
|
2.0 |
More specifically, the silver nanowire conductive film obtained in example 4 was subjected to the weather resistance test under the same conditions as in example 1, and the weather resistance test results are shown in table 10.
Table 10 weather resistance test results of silver nanowire conductive films
As can be seen from the test results of the above examples and comparative examples, under the same surface resistance condition, the silver nanowire conductive film prepared in the examples of the present invention has a lower b value, haze and higher transmittance, which indicates that the yellowing effect of the silver nanowire is alleviated and the visibility and light transmittance effects of the silver nanowire conductive film are improved by adding a blue colorant in the protective layer and using the CIE Lab color model theory. Meanwhile, the silver nanowire conductive film prepared by each embodiment has stronger weather resistance, so that the silver nanowire conductive film disclosed by the invention can be suitable for various environments, and the application range of the silver nanowire conductive film is expanded.
The present invention has been further described with reference to specific embodiments, but it should be understood that the detailed description should not be construed as limiting the spirit and scope of the present invention, and various modifications made to the above-described embodiments by those of ordinary skill in the art after reading this specification are within the scope of the present invention.